This project consists of studies on the mechanism by which chemical carcinogens induce urinary bladder tumors. The study will be concerned first with those carcinogens which have been implicated in the induction of human bladder cancer following environmental or occupational exposure. To understand the causes of clinical carcinomas that are thought to be the result of environmental or occupational exposure requires consideration of the metabolic activation of the causative agents and their reactions in the tissues of the target organs. These objectives will be approached in experiments with target tissue with methods that can be applied to human epithelium. Then the problem of candidate carcinogens will be studied by investigation of their activation in epithelium of the urinary bladder in both laboratory animals and human tissues.